AppserverIo\Appserver\ServletEngine\StandardGarbageCollector::collectGarbage PHP Method

    public function collectGarbage()
    {
        // the probability that we want to collect the garbage (float <= 1.0)
        $garbageCollectionProbability = $this->getSessionSettings()->getGarbageCollectionProbability();
        // calculate if the want to collect the garbage now
        $decimals = strlen(strrchr($garbageCollectionProbability, '.')) - 1;
        $factor = $decimals > -1 ? $decimals * 10 : 1;
        // if we can to collect the garbage, start collecting now
        if (rand(0, 100 * $factor) <= $garbageCollectionProbability * $factor) {
            // we want to know what inactivity timeout we've to check the sessions for
            $inactivityTimeout = $this->getSessionSettings()->getInactivityTimeout();
            // debug log the inactivity timeout we collect the garbage for
            if ($systemLogger = $this->getSystemLogger()) {
                $systemLogger->debug(sprintf('Now collect garbage for probability %f and inactivity timeout %d', $garbageCollectionProbability, $inactivityTimeout));
            }
            // iterate over all session and collect the session garbage
            if ($inactivityTimeout !== 0) {
                // load the session manager instance
                /** @var \AppserverIo\Appserver\ServletEngine\SessionManagerInterface $sessionManager */
                $sessionManager = $this->getApplication()->search(SessionManagerInterface::IDENTIFIER);
                // iterate over all session managers and remove the expired sessions
                foreach ($sessionManager->getSessionHandlers() as $sessionHandlerName => $sessionHandler) {
                    try {
                        if ($systemLogger && ($sessionRemovalCount = $sessionHandler->collectGarbage()) > 0) {
                            $systemLogger->debug(sprintf('Successfully removed %d session(s) by session handler \'%s\'', $sessionRemovalCount, $sessionHandlerName));
                        }
                    } catch (\Exception $e) {
                        if ($systemLogger) {
                            $systemLogger->error($e->__toString());
                        }
                    }
                }
            }
        }
    }